A low-cost sensor based on Time-Domain Reflectometry for water level monitoring in environmental applications

The implementation of water management techniques in various environmental applications requires the measurement of the level of water stored in artificial storage tanks (e.g. in cities, communities etc.) or natural reservoirs. In this paper, the design of a water-level sensor is presented, which is based on the Time-Domain Reflectometry (TDR) technique. The proposed TDR sensor comprises a sensing probe constructed using low-cost and widely-available multilayer and stainless steel tubes. A simple signal-conditioning circuit has been designed for interfacing the acquired measurements to a digital data-acquisition device through an I²C communication bus. Thus, the manufacturing cost and power consumption of the proposed sensor are relatively low, enabling its incorporation in Wireless Sensor Networks which are power-supplied by Renewable Energy Sources. The operation of the proposed sensor has been tested in a city-scale storage tank of drinking water. The experimental results verify that the proposed sensor achieves equivalent accuracy performance with a commercially available ultrasound water-level sensor, which, however, is of higher cost.